Field of Invention
The present invention relates to device and a method for parting of superimposed
fabric layers. More particularly it relates to a device and a method for parting the
possibly at least partially fused layers at the cut edges of the superimposed and
thermally cut layers of a moving fabric to facilitate further ease of subsequent
operations.
Background of invention
The usage of polyolefine woven sacks for storing of various materials like foodgrains,
sugar, cement, and fertilisers is well established. Woven sacks which are
used for storage purpose were made manually, however, with the increase in
demand, such sacks are increasingly manufactured using automated machines.
Furthermore, the sack manufacturing machine automation has experienced ever
increasing stringent quality requirement.
Automatic cutting/stitching machines used for the sack manufacturing purpose
use tubular fabric for manufacturing sacks. The fabric is thermally cut to the
required length and the cut fabric length is subsequently transferred to a stitching
station for further operation. The thermal cutting of polyolefine woven fabric
results in fusing at certain points so that irregular beads are formed at the edge of
cut. The resulting fabric suffers from fabric layer clinging together which renders
it unsuitable for downstream processing as the individual layers of the fabric need
3
to be readily separable from each other for operations such as valve forming,
stitching etc. Additionally, it is difficult to slit/part the layers apart without
unravelling them.
The absence of reliable automated means for parting of fabric layers so that they
are rendered suitable for downstream processing results fabric pieces that are
unsuitable for sack manufacturing. This in turn results in heavy losses and
deterioration in production amount and quality.
The present invention device provides an automated means for parting the
individual layers of thermo-cut tubular fabric.
Objectives
Accordingly, it is an object of the present invention to provide a device for parting
individual fabric layers in a continuous automated operation.
A further object of present invention is that the inventive device can be adapted to
any automated fabric cutting and stitching machine or similar devices where
individual layers of fabric are prone to fusing together during the cutting
operation.
4
Another object of the present invention is to provide an apparatus for
separating/parting moving thermally cut tubular fabric lengths which is simple to
operate and control and which effectively separates the fabric layers in desired
manner.
List Of Parts
1. Device of the invention
2. Fabric cut piece
2A Cut edge of fabric cut piece
2B Top layer of fabric cut piece
2C Bottom layer of fabric cut
piece
2D Portion of fabric to pass
through the device
3. Top layer-gripping surface
4. Bottom layer-gripping
surface
5. Pressure means
6. Top or upper belt
7. Bottom or lower belt
8. Stationary plate
9. Moveable pressure plate
10. Rolling member
10A Rolling pressure member
11. Top row of rolling members
12. Bottom row of rolling
members
13. Frictional lining material
List Of Figures:
Figure 1 provides a schematic diagram of the preferred embodiment of the
invention
5
Figure 1A shows the portion of the cut fabric piece going through the device of
invention
Figure 2 shows an embodiment of the invention with rolling members used for
forming layer-gripping surfaces
Figure 2A shows layer-gripping surfaces formed by frictional lining
Figure 2B shows the direction of linear speed
Figure 2C shows the line of contact
Figure 3 shows an embodiment where the layer-gripping surface is non-planar
Figure 4 shows a variation of the preferred embodiment
Figures 5 and 5A show embodiments where one planar layer-gripping surface is
formed using a belt and the other one using rolling members
Figures 6 and 7 show variations of embodiments shown in Figures 5 and 5A
Figure 8 shows a variation of the embodiment of figure 4
Figure 9 shows a variation of the embodiment of figure 2
Summary of invention:
The present invention is specially adapted for use on automated cutting and
stitching machine for polyolefine woven sack formation. On any typical such
machines, the required length of tubular woven polyolefine fabric (1) is conveyed
from the fabric roller onto a thermo-cutting device. After the fabric is cut to the
required length by the thermo-cutting machine, the fabric cut length is traversed
or transported onto a stitching station. It is important that the individual layers of
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the cut length of the fabric are not fused to each other and are separable when they
are subjected to further operations. In its simplest form, the device of the
invention has at least one top layer-gripping surface, at least one bottom layergripping
surface, and a pressure means for applying transverse pressure on the
fabric portion passing through the layer-gripping surfaces. The top and bottom
layer-gripping surfaces are typically made from friction materials with friction
coefficient that is greater than that of the fabric. The device is located downstream
of the fabric cutting station.
Detailed description of invention:
The present invention is specially adapted for use on automated cutting and
stitching machine for polyolefine woven sack formation. On any typical such
machines, the required length of tubular woven polyolefine fabric (1) is conveyed
from the fabric roller onto a thermo-cutting device. After the fabric is cut to the
required length by the thermo-cutting machine, the fabric cut length is traversed
or transported onto a stitching station. It is important that the individual layers of
the cut length of the fabric are not fused to each other and are separable when they
are subjected to further operations. For this purpose, during the transportation of
cut fabric lengths, the fabric end where the individual layers need to be parted is
fed into the device of present invention. This is illustrated in Figure 1.
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The present invention may also be used on fabric made of any other material such
as plastics, paper, paper laminated with plastic, or any other nonwoven fabric.
The device of the invention is a device (1) for separating the layers of a sackmaking
fabric piece (2) at its cut edge (2A) where said edge is possibly at least
partly fused (see detail A of Figure 1) during the cutting operation when such
cutting operation is carried out using a thermo-cutting or thermo-mechanical
cutting technique. Even in the instances where there is no fusing at the cut edge,
the fabric benefits from passing through the device in that it is always desirable
for the downstream operations to have the individual layers of the cut fabric piece
separated from each other (see detail B of Figure 1).
In its simplest form, the device (1) has at least one top layer-gripping surface (3),
at least one bottom layer-gripping surface (4), and a pressure means (5) for
applying transverse pressure on the fabric portion (2D) passing through the layergripping
surfaces (3, 4). The top and bottom layer-gripping surfaces (3, 4) are
typically made from materials with friction coefficient that is greater than that of
the fabric. The device is located downstream of the fabric cutting station.
Figure 1A shows the portion (2D) of the fabric cut piece containing the cut edge
(2A). This is the portion (2D), which is typically up to a few millimetres in
dimension, which passes through the device (1) of the invention. The width of this
8
portion varies depending on the fabric or the thermo-mechanical cutting technique
used to cut the fabric. The width must be large enough so that all areas of the
fabric where fusing of layers of fabric may take place during the thermomechanical
cutting process pass through the device of the invention.
A layer-gripping surface (3, 4) may be contiguous or comprises a number of
discrete surfaces.
While the portion of the fabric containing the cut edge (2A) of the cut fabric piece
(2) passes through the two layer-gripping surfaces (3,4), the top and bottom layers
(2B, 2C) of the fabric (2) at its cut edge (2A) are pressed together gently by the
pressure means (5) that is a part of the device. During the passage of the fabric cut
piece (2) through the device (1), the fabric layers (2B, 2C) are being frictionally
gripped by the layer-gripping surfaces (3, 4). The layer-gripping surfaces (3, 4)
are themselves driven into a motion such that it facilitates the forward motion of
the fabric cut piece (2).
One key aspect of the device of the invention is that the any one of the layergripping
surfaces (3, 4) has a different linear speed at the respective points or
zones of contact with the cut fabric piece (2) than that of the other layer-gripping
surface (3, 4).
9
A point of contact for the purpose of this document is defined as a point where a
layer-gripping surface (3, 4) contacts a layer (2B, 2C) of fabric cut piece (2). In
some variations of the invention, there are distinct points of contact (see Figures 2
and 3 for example), whereas in some other variations, entire portions of fabric
come in contact with a layer-gripping surface (3, 4), in which case, the term
contact area is more appropriate – for example, in the variations of the invention
where a belt is used for a layer-gripping surface.
In the case, where the layer-gripping surface (3, 4) is formed by a rolling member
(10) in the form of a cylinder, a contact line is formed rather than a contact point
(see detail D of Figure 2). A common term – contact zone – is therefore used to
represent all different types of contact between a layer-gripping surface (3, 4) and
a fabric layer (2B, 2C). It is important that at least one contact zone must be
formed by each of the layer-gripping surface (3, 4) with a layer (2B, 2C) of cut
fabric piece (2).
For the purpose of this document, the linear speed is defined as the speed of the
layer-gripping surface (3, 4) in the direction of the fabric passage at the points or
zones of contact (see Figure 2B). This, together with the fact that the layergripping
surfaces (3, 4) have a frictional grip on the fabric (2), exerts a shear force
on the portion of fabric that is under the grip. The shear force is sufficient in
magnitude to break the fused beads formed at the cut edge (2A) thereby separating
10
the two layers (2B, 2C) of the fabric (2) at the edge (2A), whereby the cut edge
(2A) becomes fully open.
As shown in Figure 1, in one alternative of the device, the layer-gripping surfaces
(3, 4) comprise a pair of belts – an upper or top belt (6) and a lower or bottom belt
(7). The layer-gripping surfaces formed in this variation of the invention are of
contiguous type. The pressure means (5) presses both belts (6, 7) together. Each
belt (6, 7) is driven individually. Both the belts (6, 7) are driven such that fabric
movement is facilitated through them. With an objective of separating the
possibly at least partly fused layers of tubular fabric at cut edge (2A), the linear
speeds of the individual belts (6, 7) at the points or areas or zones of contact are
kept different from each other. Once again, as a result of the differential speed of
the two belts (6, 7), the individual layers (2B, 2C) of fabric cut piece (2) move at
differential speeds with respect to each other for the period the fabric cut piece (2)
is passing through the device. This, along with the pressure exerted by the
pressure means (5), introduces a shear force between the two individual layers
(2B, 2C) at the cut edge (2A) of the cut fabric piece (2).
In one variation of the invention, the linear speed of belts (6, 7) may be
intermittently varied such that desired parting of superimposed fabric layers (2B,
2C) occurs.
11
The pressure means, in the case where the upper and lower belts (6, 7) are
employed, comprises a stationary plate (8) below the lower belt (7) and a
moveable pressure plate (9) which suitably presses the upper belt (6) against the
bottom belt (7) when the fabric passes between the belts (6, 7). The surfaces of the
moveable pressure plate (9) and the bottom stationary plate (8) that face said
fabric cut piece (2) are planar or flat. Alternatively, the moveable pressure plate
(9) or the stationary plate (8) may be non-planar (see Figure 8) but of a
configuration that allows the passage of cut fabric piece through them without
forming creases or crimps.
The load on the pressure plate (9) is applied hydraulically or pneumatically or by
any other suitable means, for example springs or dead weight. The preferred
loading system is a pneumatic cylinder with ability to adjust the pneumatic
pressure.
The layer-gripping surfaces (3, 4) may be of identical type or may have different
surface texture for the purpose of gripping the fabric. The movement of each
layer-gripping surface (3, 4) is controlled individually through means such as an
electric drive motor.
A variation of the invention where two belts (6, 7) are used as layer-gripping
surfaces (3, 4) is disclosed (see Figure 4). Here, instead of the top moveable
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pressure plate (9), a set of at least one rolling pressure members (10A) is provided
which is capable of, using hydraulic or pneumatic means, pressing said top layer
of said fabric down onto said bottom layer of said fabric supported by the
stationary plate. The rolling pressure member (10A) applies pressure to the top
belt using hydraulic or pneumatic means.
There are several further variations of the device. In one variation (see Figure 2), a
number of rolling members (10) are provided in two rows, a top (or upper) row
(11) and a bottom (or lower) row (12). The rolling members (10) may be in the
form of a cylinder or spheres or any other shapes that enable the rolling members
(10) to rotate symmetrically around their longitudinal axes (shown by the '+' mark
shown on the rolling members in Figures 2-9). The rolling members (10), when in
the form of a cylinder, form a number of contact lines with the fabric layers (2B,
2C). The rolling members (10), when in the form of a sphere, form contact points
with the fabric layers (2B, 2C). It is at these lines or points of contact, the rolling
members (10) exert a grip over the fabric layers (2B, 2C). These contact lines or
points, as the case may be, together, form the non-contiguous top or bottom layergripping
surface (3, 4). Figure 3 shows an embodiment of the invention where
such non-contiguous layer-gripping surfaces are formed.
As shown in Figure 2A, a separate frictional surface (13) in the form of a lining or
a layer may be provided on the outer face of the rolling members (10) or on the
13
surfaces of the belts (6, 7) that come in contact with the layers (2B, 2C) of the
fabric cut piece (2).
In the case where two rows (11, 12) of rolling members (10) are used as layergripping
surfaces (3, 4), the rolling members (10) themselves form a part of the
pressure means (5). In this instance the rolling members (10) of the upper row
(11) is pressed hydraulically or pneumatically against the rolling members (10) of
the lower row (12), thereby exerting pressure on the fabric layers (2B, 2C).
As shown in Figure 2, the rolling members (10) of the top row (11) rotate in an
anticlockwise direction when viewed as shown in Figure 2. In this position of
viewing, the rolling members (10) of the bottom row (12) rotate in clockwise
direction. The rolling members (10) rotate at rotational speeds such that the linear
speed of all rolling members of a given row (11, 12) at the respective contact
points or zones is of the same magnitude. The linear speed of the rolling members
(10) of any given row (11 or 12) at the respective contact points or zones is
different from the linear speed of the rolling members (10) of the other row (12 or
11) so that there is a differential linear speed imparted to the individual layers
(2B, 2C) of the fabric cut piece (2) passing between the rows (11, 12). The linear
speed is measured at the point or zone of contact of any rolling member (10) with
the fabric layers (2B, 2C) and measured in the direction of motion of the fabric cut
piece (2).
14
As seen from detail C of Figure 2, the contact points the rolling members (10)
with the fabric layers (2B, 2C) are in a straight line or a plane that is parallel to the
direction of movement of the fabric. The rolling members (10) in this instance are
of spherical shape.
As seen from Figure 2C, a line of contact is formed by the rolling member (10)
with a fabric layer (2B or 2C), in the case where the rolling member is cylindrical
in shape.
In any variation of the invention where rolling members (10) are used to form a
layer-gripping surface (3 or 4), the number of rolling members (10) and their
position is such that at least one contact point is formed with a fabric layer (2B or
2C) by a rolling member from each row (11 and 12).
In yet another embodiment, when there are more than two contact points or zones,
the rolling members (10) are so positioned that the contact points of rolling
members (10) of any given layer-gripping surface (3, 4) are collinear (see detail C
of Figure 2). In another embodiment, embodiment, when there are more than two
contact points, the rolling members (10) are so positioned that the contact points
of rolling members (10) of any given layer-gripping surface (3, 4) are non-linearly
positioned. (See detail C of Figure 3.)
15
There are several other aspects of the invention. In one such aspect, material used
for forming the top and bottom layer-gripping surfaces may be identical and the
layer-gripping surfaces may have identical geometrical features. Alternatively
they may be made of different materials and may have different geometrical
features. The frictional surfaces used for the top and bottom layer-gripping
surfaces (3, 4) may also use frictional material of identical frictional coefficient or
different frictional coefficient. In particular, the pair of belts (6, 7) or the rolling
members (10) used for forming the layer-gripping surfaces (3, 4) may be made of
identical material and be of identical geometrical features. Alternatively they may
be made of different materials and may have different geometrical features.
It should also be noted that the rolling members (10) and the belts (6, 7) are the
structural parts of a layer-gripping surface (3, 4). These parts themselves may be
made using structural materials that have adequate frictional properties to serve as
layer-gripping surfaces. On the other hand, these structural parts may be lined or
layered or coated using frictional material (13) with adequate coefficient of
friction to serve as layer gripping surfaces (3, 4).
In a yet further aspect of the invention, the materials used for the structural parts
of the layer-gripping surfaces is selected from a group of materials comprising
rubber, polyurethane, or a similar synthetic material. In another embodiment a
separate lining/layer/coating made from rubber, polyurethane or a similar
16
synthetic material is provided on the outer surface of the structural part of the
layer-gripping surface. Where there is a lining/coating used, the structural material
used for forming belts or rolling members may also be metal or plastic.
In any variation of the invention, all layer-gripping surfaces (3, 4) have a higher
friction coefficient than the fabric.
The movement of each of the rolling members (10) may be controlled or driven
individually. Alternatively, the movement of at least two rolling members (10)
may be controlled or driven as a group.
In a still further aspect of the invention, the movement of the top or bottom layergripping
surfaces (3, 4), or their individual components, is controlled using means
such as an electric drive motor.
It is possible that the fabric may be made of more than two layers.
As shown in Figure 5, in a further aspect of the invention, the top layer-gripping
surface (3) is in the form of the top belt (6) and said bottom layer-gripping surface
is in the form of a set of rolling members (10). In this circumstance, the pressure
means comprise the moveable pressure plate (9) capable of pressing the top belt
17
(6) against said fabric cut piece (2) supported on its bottom face by said set of
rolling members (10) which also act as bottom layer-gripping surface (4).
As shown in Figure 5A, in another aspect of the invention, the bottom layergripping
surface is in the form of a belt (7) and said top layer-gripping surface (3)
is in the form of a set of rolling members (10). In this circumstance, the pressure
means is in the form of said set of rolling members (10) that press against said
fabric supported on its bottom face by the stationary plate (8) provided below said
bottom layer-gripping surface (4). As shown in Figure 6, the stationary plate (8)
may be non-planar.
As shown in Figure 8, in one variation of the invention, the surfaces of the
moveable plate (9) and the bottom stationary plate (8) that face said fabric may be
non-planar.
As shown in Figure 9, and as a still further aspect of the invention, line joining the
centres of the rolling members (10) forming either the top or bottom layergripping
surfaces (3, 4) is either curvilinear or straight but non-parallel with the
direction of fabric movement. Any rolling member (1) may be of the same
diameter as any other rolling member (10). An example of this is where any
rolling member (10) may be of different diameter (see Figure 9) than any other
rolling member (10). However, in such situation the linear speed of all rolling
18
members (10) from any given row (11 or 12) at the point of contact with the fabric
must be the same.
In another aspect of the invention, the rolling members (10) of the upper and
lower rows (11, 12) are positioned so that the contact points formed by all rolling
members (10) of any row (11 and/or, 12) with the fabric layers (2B, 2C) are in a
straight line.
In a further aspect of the invention, any of the said rolling members (10) may be
of different diameter than any of the other said rolling members (10).
The present invention also discloses a method of separating individual layers (2B,
2C) of a polyolefine woven fabric cut piece (2). Such layers may possibly be at
least partly fused during a thermo-cutting process. The process comprises the step
of putting the portion of cut fabric length (2) containing the cut edge (2A)
between a pair of moving layer-gripping surfaces (3, 4) under the effect of
transverse pressure and such that the layer-gripping surfaces (3, 4) move at a
differential linear speed with each other at their points of contact with the fabric
layers (2B, 2C).
The step of introducing a shear force used in the method for parting of
superimposed fabric layers (2B, 2C) of the fabric cut piece (2) comprises the steps
of:
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- providing a device for parting of fabric as disclosed in any variations
of the invention
- driving the layer-gripping surfaces (3, 4) so that the movement of the
cut edge (2A) of the cut fabric piece (2) of is facilitated between said
layer-gripping surfaces (3, 4)
- while the fabric cut piece (2) is passing through said layer-gripping
surfaces (3, 4), adjusting the linear speeds of said layer gripping
surfaces (3, 4) at the contact points, such that there is a linear speed
differential between the two layer-gripping surfaces (3, 4),
- simultaneously with the step of creating a linear speed differential,
applying pressure to the top layer-gripping surface (3) so that it is
pressed against the bottom layer-gripping surface (4).
The invention also discloses a method for parting of superimposed fabric layers
where said top and bottom layer-gripping surfaces are in the form of a pair of
belts having frictional surfaces, namely a top belt (3) and a bottom belt (4).
In a further variation, the invention discloses a method for parting of
superimposed fabric layers where said top and bottom layer-gripping surfaces are
in the form of sets of rolling members, said rolling members being arranged in
two rows, namely an upper row and a lower row.
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In yet another variation, the invention discloses a method for parting of
superimposed fabric layers where the top layer-gripping surface is in the form of a
belt having a frictional surface and said bottom layer-gripping surface is in the
form of a set of rolling members provided with frictional outer surfaces.
Finally, the invention also discloses a method for parting of superimposed fabric
layers where the bottom layer-gripping surface is in the form of a belt having a
frictional surface and said top layer-gripping surface is in the form of a set of
rolling members provided with frictional outer surfaces.
It is therefore evident from the foregoing discussion that the invention has the
following embodiments.
1. A device for parting of superimposed fabric layers of a fabric piece cut
using a thermo-mechanical cutting technique on automated cuttingstitching/
sack-making machine, said device being positioned downstream
of the fabric cutting station, said fabric comprising at least a top and a
bottom layer that are possibly at least partly fused at the cut edge,
characterised in that said device comprises has at least one top layergripping
surface, at least one bottom layer-gripping surface, and a pressure
means for applying transverse pressure on said fabric as said fabric passes
through said surfaces, wherein said top and bottom layer-gripping surfaces
21
frictionally grip top and bottom layers of cut portion of said fabric piece
passing through them, and wherein at any point of contact of said layergripping
surfaces with said fabric piece, any one layer-gripping surface
moves at a different linear speed relative to that of the other layer-gripping
surface.
2. A device for parting of superimposed fabric layers as disclosed in
embodiment 1, characterised in that the linear speed of any one of the
layer-gripping surfaces is up to 50% higher or lower than that of the other
layer-gripping surface.
3. A device for parting of fabric as disclosed in embodiments 1-2,
characterised in that the linear speed of either or both of said layergripping
surfaces varies intermittently.
4. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-3, characterised in that the movement of each of said
layer-gripping surfaces is controlled individually.
5. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-4, characterised in that the movement of said layergripping
surfaces is controlled using means such as an electric drive
motor.
6. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-5, characterised in that the materials used for said layergripping
surfaces is rubber, polyurethane, or similar synthetic material.
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7. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-6, characterised in that said cut fabric piece may be made
of more than two layers.
8. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-7, characterised in that the layer-gripping surface has a
higher friction coefficient than the fabric.
9. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-8, wherein said top and bottom layer-gripping surfaces
have same or different coefficients of friction.
10. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-9, characterised in that said top and bottom layer-gripping
surfaces are in the form of a pair of belts having frictional surfaces,
namely a top belt (3) and a bottom belt (4).
11. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-10, characterised in that said pressure means comprise a
stationary plate provided below the bottom belt and a moveable pressure
plate capable of pressing the top belt against the bottom belt supported by
said stationary plate, wherein when said fabric passes between the belts,
the top belt is pressed down onto the bottom belt with the help of said
moveable pressure plate.
12. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-11, characterised in that the load on the pressure plate is
23
applied hydraulically or pneumatically or with any other suitable means
such as spring or dead weight.
13. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-12, characterised in that the pair of belts may be of
identical type or may have different surface texture.
14. A device for parting of superimposed fabric layers as disclosed in
embodiment 13, wherein surfaces of said belts are lined, or layered, or
coated with frictional material having a friction coefficient greater than
that of cut fabric piece.
15. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-9, characterised in that said top and bottom layer-gripping
surfaces are in the form of sets of rolling members, said rolling members
being arranged in two rows, namely an upper row and a lower row.
16. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-15, wherein surfaces of said belts and said rolling
members are lined, or layered, or coated with frictional material having a
friction coefficient greater than that of cut fabric piece.
17. A device for parting of superimposed fabric layers as disclosed in
embodiment 16, characterised in that said pressure means is in the form
spring-loaded or hydraulically-loaded or pneumatically-loaded means to
exert pressure on said upper or low rows or on both rows, and wherein
24
said bottom layer of the cut fabric piece is supported by a second
stationary plate.
18. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-9, characterised in that said top layer-gripping surface is in
the form of a belt having a frictional surface and said bottom layergripping
surface is in the form of a set of rolling members provided with
frictional outer surfaces.
19. A device for parting of superimposed fabric layers as disclosed in
embodiment 18, characterised in that said pressure means comprise a
moveable pressure plate capable of pressing the top belt against said fabric
supported on the bottom by said set of rolling members which also act as
bottom layer-gripping surface.
20. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-9, characterised in that said bottom layer-gripping surface
is in the form of a belt having a frictional surface and said top layergripping
surface is in the form of a set of rolling members provided with
frictional outer surfaces.
21. A device for parting of superimposed fabric layers as disclosed in
embodiment 20, characterised in that said pressure means is in the form of
said set of rolling members that press against said fabric supported by a
stationary plate provided below said bottom layer-gripping surface.
25
22. A device for parting of superimposed fabric layers as disclosed in
embodiments 15-21, wherein the line joining the centres of the rolling
members supporting either the top or bottom layer-gripping surfaces is
either curvilinear or non-parallel with the direction of fabric movement.
23. A device for parting of superimposed fabric layers as disclosed in
embodiments 2-22, characterised in that the surfaces of the moveable plate
and the bottom stationary plate that face said fabric are non-planar.
24. A device for parting of superimposed fabric layers as disclosed in
embodiments 15-23, characterised the rolling members of the said upper
and lower rows are positioned such that the contact points or zones formed
between corresponding rolling members are in a straight line.
25. A device for parting of superimposed fabric layers as disclosed in
embodiments 24-25, characterised in that any of the said rolling members
may be of different diameter than any of the other said rolling members.
26. A device for parting of superimposed fabric layers as disclosed in
embodiment 25, characterised in that the total number of contact points
formed is at least two, and wherein at least one contact point is formed by
each of said layer-gripping surfaces with a layer of said cut fabric piece.
27. A device for parting of superimposed fabric layers as disclosed in
embodiments 15-26, characterised in that said rolling members are driven
in groups of more than one.
26
28. A method of separating individual layers of a fabric cut piece which are
possibly at least partly fused during a thermo-cutting process, said method
comprising the step of passing the portion of cut fabric length containing
the cut edge between a pair of moving layer-gripping surfaces under the
effect of transverse pressure and such that the layer-gripping surfaces
move at a differential linear speed with each other at their points of contact
with the fabric layers.
29. A method for parting of superimposed fabric layers as disclosed in
embodiment 28, characterised in that said shear force is introduced by
pressing together the two layers of said fabric cut piece and
simultaneously moving the two layers at differential linear speeds with
respect to each other.
30. A method for parting of superimposed fabric layers as disclosed in
embodiments 28-29, wherein said step of introducing a shear force
comprises the steps of:
- providing a device for parting of fabric as claimed in any of claims 1 to
27,
- driving said layer-gripping surfaces so that the movement of the cut
edge said cut fabric piece of is facilitated between said layer-gripping
surfaces,
- while the fabric is passing through said layer-gripping surfaces,
adjusting the linear speeds of said layer gripping surfaces at the contact
27
points, such that there is a linear speed differential between the two
layer-gripping surfaces,
- simultaneously with the step of creating a linear speed differential,
applying pressure to the top layer-gripping surface so that it is pressed
against the bottom layer-gripping surface.
31. A method for parting of superimposed fabric layers as disclosed in
embodiments 28-30, characterised in that said top and bottom layergripping
surfaces are in the form of a pair of belts having frictional
surfaces, namely a top belt and a bottom belt.
32. A method for parting of superimposed fabric layers as disclosed in
embodiments 28-30, characterised in that said top and bottom layergripping
surfaces are in the form of sets of rolling members, said rolling
members being arranged in two rows, namely an upper row and a lower
row.
33. A method for parting of superimposed fabric layers as disclosed in
embodiments 28-30, characterised in that said top layer-gripping surface is
in the form of a belt having a frictional surface and said bottom layergripping
surface is in the form of a set of rolling members provided with
frictional outer surfaces.
34. A method for parting of superimposed fabric layers as disclosed in
embodiments 28-33, characterised in that said bottom layer-gripping
surface is in the form of a belt having a frictional surface and said top
28
layer-gripping surface is in the form of a set of rolling members provided
with frictional outer surfaces.
35. A device for parting of superimposed fabric layers as disclosed in
embodiments 1-27, characterised in that said fabric is a woven fabric made
of polyolefine or a nonwoven fabric made of paper or plastic, or paper
lined with plastic.
36. A method for parting of superimposed fabric layers as disclosed in
embodiments 28-34, characterised in that said fabric is a woven fabric
made of polyolefine or a nonwoven fabric made of paper or plastic, or
paper lined with plastic.
While the above description contains much specificity, these should not be
construed as limitation in the scope of the invention, but rather as an
exemplification of the preferred embodiments thereof. It must be realized that
modifications and variations are possible based on the disclosure given above
without departing from the spirit and scope of the invention. Accordingly, the
scope of the invention should be determined not by the embodiments illustrated,
but by the appended claims and their legal equivalents.
29

We claim:
1. A device for parting of superimposed fabric layers of a fabric piece cut using a
thermo-mechanical cutting technique on automated cutting-stitching/sackmaking
machine, said device being positioned downstream of the fabric cutting
station, said fabric comprising at least a top and a bottom layer that are
possibly at least partly fused at the cut edge, characterised in that said device
comprises has at least one top layer-gripping surface, at least one bottom layergripping
surface, and a pressure means for applying transverse pressure on said
fabric as said fabric passes through said surfaces, wherein said top and bottom
layer-gripping surfaces frictionally grip top and bottom layers of cut portion of
said fabric piece passing through them, and wherein at any point of contact of
said layer-gripping surfaces with said fabric piece, any one layer-gripping
surface moves at a different linear speed relative to that of the other layergripping
surface.
2. A device for parting of superimposed fabric layers as claimed in claim 1,
characterised in that the linear speed of any one of the layer-gripping surfaces
is up to 50% higher or lower than that of the other layer-gripping surface.
3. A device for parting of fabric as claimed in claims 1-2, characterised in that the
linear speed of either or both of said layer-gripping surfaces varies
intermittently.
30
4. A device for parting of superimposed fabric layers as claimed in claims 1-
3, characterised in that the movement of each of said layer-gripping
surfaces is controlled individually.
5. A device for parting of superimposed fabric layers as claimed in claims 1-
4, characterised in that the movement of said layer-gripping surfaces is
controlled using means such as an electric drive motor.
6. A device for parting of superimposed fabric layers as claimed in claims 1-
5, characterised in that the materials used for said layer-gripping surfaces
is rubber, polyurethane, or similar synthetic material.
7. A device for parting of superimposed fabric layers as claimed in claims 1-
6, characterised in that said cut fabric piece may be made of more than two
layers.
8. A device for parting of superimposed fabric layers as claimed in claims 1-
7, characterised in that the layer-gripping surface has a higher friction
coefficient than the fabric.
9. A device for parting of superimposed fabric layers as claimed in claims 1-
8, wherein said top and bottom layer-gripping surfaces have same or
different coefficients of friction.
10. A device for parting of superimposed fabric layers as claimed in claims 1-
9, characterised in that said top and bottom layer-gripping surfaces are in
the form of a pair of belts having frictional surfaces, namely a top belt (3)
and a bottom belt (4).
31
11. A device for parting of superimposed fabric layers as claimed in claims 1-
10, characterised in that said pressure means comprise a stationary plate
provided below the bottom belt and a moveable pressure plate capable of
pressing the top belt against the bottom belt supported by said stationary
plate, wherein when said fabric passes between the belts, the top belt is
pressed down onto the bottom belt with the help of said moveable pressure
plate.
12. A device for parting of superimposed fabric layers as claimed in claims 1-
11, characterised in that the load on the pressure plate is applied
hydraulically or pneumatically or with any other suitable means such as
spring or dead weight.
13. A device for parting of superimposed fabric layers as claimed in claims 1-
12, characterised in that the pair of belts may be of identical type or may
have different surface texture.
14. A device for parting of superimposed fabric layers as claimed in claims
10-13, wherein surfaces of said belts are lined, or layered, or coated with
frictional material having a friction coefficient greater than that of cut
fabric piece.
15. A device for parting of superimposed fabric layers as claimed in claims 1-
9, characterised in that said top and bottom layer-gripping surfaces are in
the form of sets of rolling members, said rolling members being arranged
in two rows, namely an upper row and a lower row.
32
16. A device for parting of superimposed fabric layers as claimed in claims 1-
15, wherein surfaces of said belts and said rolling members are lined, or
layered, or coated with frictional material having a friction coefficient
greater than that of cut fabric piece.
17. A device for parting of superimposed fabric layers as claimed in claim 16,
characterised in that said pressure means is in the form spring-loaded or
hydraulically-loaded or pneumatically-loaded means to exert pressure on
said upper or low rows or on both rows, and wherein said bottom layer of
the cut fabric piece is supported by a second stationary plate.
18. A device for parting of superimposed fabric layers as claimed in claims 1-
9, characterised in that said top layer-gripping surface is in the form of a
belt having a frictional surface and said bottom layer-gripping surface is in
the form of a set of rolling members provided with frictional outer
surfaces.
19. A device for parting of superimposed fabric layers as claimed in claim 18,
characterised in that said pressure means comprise a moveable pressure
plate capable of pressing the top belt against said fabric supported on the
bottom by said set of rolling members which also act as bottom layergripping
surface.
20. A device for parting of superimposed fabric layers as claimed in claims 1-
9, characterised in that said bottom layer-gripping surface is in the form of
a belt having a frictional surface and said top layer-gripping surface is in
33
the form of a set of rolling members provided with frictional outer
surfaces.
21. A device for parting of superimposed fabric layers as claimed in claim 20,
characterised in that said pressure means is in the form of said set of
rolling members that press against said fabric supported by a stationary
plate provided below said bottom layer-gripping surface.
22. A device for parting of superimposed fabric layers as claimed in claims
15-21, wherein the line joining the centres of the rolling members
supporting either the top or bottom layer-gripping surfaces is either
curvilinear or non-parallel with the direction of fabric movement.
23. A device for parting of superimposed fabric layers as claimed in claims 2-
22, characterised in that the surfaces of the moveable plate and the bottom
stationary plate that face said fabric are non-planar.
24. A device for parting of superimposed fabric layers as claimed in claims
15-23, characterised the rolling members of the said upper and lower rows
are positioned such that the contact points or zones formed between
corresponding rolling members are in a straight line.
25. A device for parting of superimposed fabric layers as claimed in claim 24,
characterised in that any of the said rolling members may be of different
diameter than any of the other said rolling members.
26. A device for parting of superimposed fabric layers as claimed in claims
24-25, characterised in that the total number of contact points formed is at
34
least two, and wherein at least one contact point is formed by each of said
layer-gripping surfaces with a layer of said cut fabric piece.
27. A device for parting of superimposed fabric layers as claimed in claims
15-26, characterised in that said rolling members are driven in groups of
more than one.
28. A method of separating individual layers of a fabric cut piece which are
possibly at least partly fused during a thermo-cutting process, said method
comprising the step of passing the portion of cut fabric length containing
the cut edge between a pair of moving layer-gripping surfaces under the
effect of transverse pressure and such that the layer-gripping surfaces
move at a differential linear speed with each other at their points of contact
with the fabric layers.
29. A method for parting of superimposed fabric layers as claimed in claim
28, characterised in that said shear force is introduced by pressing together
the two layers of said fabric cut piece and simultaneously moving the two
layers at differential linear speeds with respect to each other.
30. A method for parting of superimposed fabric layers as claimed in claims
28-29, wherein said step of introducing a shear force comprises the steps
of:
- providing a device for parting of fabric as claimed in any of claims 1 to
27,
35
- driving said layer-gripping surfaces so that the movement of the cut
edge said cut fabric piece of is facilitated between said layer-gripping
surfaces,
- while the fabric is passing through said layer-gripping surfaces,
adjusting the linear speeds of said layer gripping surfaces at the contact
points, such that there is a linear speed differential between the two
layer-gripping surfaces,
- simultaneously with the step of creating a linear speed differential,
applying pressure to the top layer-gripping surface so that it is pressed
against the bottom layer-gripping surface.
31. A method for parting of superimposed fabric layers as claimed in claims
28-30, characterised in that said top and bottom layer-gripping surfaces are
in the form of a pair of belts having frictional surfaces, namely a top belt
and a bottom belt.
32. A method for parting of superimposed fabric layers as claimed in claims
28-30, characterised in that said top and bottom layer-gripping surfaces are
in the form of sets of rolling members, said rolling members being
arranged in two rows, namely an upper row and a lower row.
33. A method for parting of superimposed fabric layers as claimed in claims
28-30, characterised in that said top layer-gripping surface is in the form
of a belt having a frictional surface and said bottom layer-gripping surface
36
is in the form of a set of rolling members provided with frictional outer
surfaces.
34. A method for parting of superimposed fabric layers as claimed in claims
28-33, characterised in that said bottom layer-gripping surface is in the
form of a belt having a frictional surface and said top layer-gripping
surface is in the form of a set of rolling members provided with frictional
outer surfaces.
35. A device for parting of superimposed fabric layers as claimed in claims 1-
27, characterised in that said fabric is a woven fabric made of polyolefine
or a nonwoven fabric made of paper or plastic, or paper lined with plastic.
36. A method for parting of superimposed fabric layers as claimed in claims
28-34, characterised in that said fabric is a woven fabric made of
polyolefine or a nonwoven fabric made of paper or plastic, or paper lined
with plastic.